Miniature rotatable electrical contact components for printed circuit board applications are widely used in electrical and electronic equipment. One type of suitable contact structure for such components is shown in U.S. Pat. No. 3,940,198, issued in the name of Andersen et al, on Feb. 24, 1976 and assigned to the assignee of the present invention. These electrical components also consist of a rotor which has a bushing that is formed with a shoulder so that when the bushing protrudes through an aperture in the printed circuit board the shoulder engages the bottom of the board to hold the rotatable member in place. The contact structure is riveted to the rotor so that it may engage the electrical circuitry formed on the upper surface of the printed circuit board. In many applications it is desirable to provide a stop so that only limited rotation of the rotor is allowed. The stop member may be provided by a post that extends down into an aperture in the printed circuit board which prevents rotation of the stop member.
It is also desirable in many applications to include detent provisions so that the rotation of the rotor may be accurately controlled from one step to the next. Detents are conventionally provided by means of a spring which is fixed to a stationary support. The rotor is generally provided with a plurality of grooves which receive the end of the spring in succession as the rotor is rotated, thereby allowing the rotor to be moved from one position to the next. The use of a separate spring, however, presents undesirable complications. This is because the spring must either be separately attached to the printed circuit board thereby taking up valuable printed circuit area, and necessitating modification of the printed circuit board in many cases, in order to secure the spring to the board. Another way of securing the spring to a station and support would be to secure it to a stationary part of the housing of the component itself. However, this complicates the housing construction and can appreciably increase the size and cost of the component. The snap-on stop ring of the present invention functions both to stop the rotor at a predetermined position and provides detent action due to its unique construction and to the configuration of a retaining aperture in the printed circuit board, whereby rotational movement of the stop member is prevented by the rectangular shape of the aperture but transverse flexing motion of the stop member is allowed to provide the detent function. The present invention thereby achieves an extremely simple, small and cost effective structure.